If you try and book an appointment but see the error "equipment isn't available in this room" it is because the equipment required for that service has not been allocated to the room being booked.
Go to admin/location/equipment and click on the equipment in question. Here you can select the rooms that this equipment can be used in and also the priority of the rooms.
Ensure that the rooms the service can be performed in matches the rooms that the equipment is selected for. If there is a mismatch here, there can be clashes that will stop you being able to book the service.